Safety-fuse.



F. DJ'REYNOLDS & J. SACHS.

, SAFETY FUSE. APPLICATION FILED APR. 17' 1906-.

Patented Oct. 13,1908.

. mxeonaei,

, tube.

'.tioular portion of :spe cation.

' conductor employed in these y and at timesthis so-c UmTnn STATES PATENT el m.

FRA K nmEYNoLDs AND 'Josnrn'sscns-or HARTFORD, con-snmlour asslenons TO'THE "sirens compan OF'HARTFORD, CONNECTICUT, A ooRroRA'rIoN or ooNNEqrIoUT.

emmsn.

:and 'Josnien :Saons, .=bot'h citizens of -:the

lhiited fitates, and residents of HartfordQin the county of Hartford and State -of -Oonnecticut have invented an Improvement in Safet J uses, of which the follow-mg is "a Our invention relates to that class .of safetyfuses known as inclosed fuses in which a fumble conductor is incased within a suitable tube and surrounded by a -non-conductlng filling material. Heretofore lthe fusible fuses has commonl been one of even cross section throughout its length, and which when car-'- rymg an excess current, frequently remains hanging in a molten condition and consequently has not properly broken the circuit, and thereby the fuse accurate and unreliable. The maintenance of the fusible conductor in-this molten condit on is due to the fact that the fuse strip I made o'f-lead,,ti'n,'zinc, or a similar or alloys of the same, is covered by an nd and is also closely surrounded by the insulating material filling the tube so that the molten metal has no piplportunity to flow,

alle anging condition continues until the volatilizing is reached and causes the burning o temfperature Theobjelct of our. invention is to means whereby the re ture of the or conductor. is insure as soon as a desire port on of the same has attained a molten condition and in order toaccomplish this re sult we so construct the fuse stri as to cause the heat generated therein, by till: passage of thecurrent', to. be concentrated at some par- "the fuse strip where the to ture ls desired+preferably the center.

present invention, the

' carrying out our desir d resultis obtained by d y the heat radiatlng properties of the. fuse stn at the-rupture .pomt, or rather incre eat radiatin with flattened it er side "of' end we emp oy a tube properties of thestri at all po nts ex t therupture' point an to this or casing- ,ute nninals or end. caps, therefore, a fuse strip electrioally connected to theend caps and rovided slortl'ons similarly p aced on filling of insulating in surro nd- Speeflleation of Letter-"Patent. a puueoh msea mu, me. leflal-Io..81-2,m;

device is rendered in- 3 'tion 3'which retalns tion. We also em loy aninsulatlng mate- 9 fusestrip d and filling the fuse e central rupture portion,

"Patented'Och 1a, 1908.

' -ingtthefueestrip within the-tube, as

ihereinafter more :particularly. described.

"lnrthe Figure -1 is arcentral longitudinal section of asafet fuse illustrating our :present invention, g iew taken at right angles to that shown in Y a designates a tube or casi preferably made of :msulating'material, an 6-6 .are me,- =tallicrend caps or terminals fitting over the respective ends of the tube aand having electrically connected thereto the fuse strip terminals 0 c. i p tdrdesignates .aconduoto'r or fuse-strip of ea alloy of the same, extending between and electrically connected to the fuse stnfil ter- ,min als c, c. This fuse strip (1 is origin uniform and'preferably circular cross section throiighout its length an irafter' the respec- 'tive ends thereof have been electrically connected to the terminals ctthe strip is placed in a press or other equivalentdevice to pro duce the flattened ortions 2 similarly placed with reference to t its original cross-secrial e surrounding t the tube a. 1 l

Now as is generally known the heat genervaries inversely as the ated in a conductor cross section and direcgg consequently, if the or section is constant Fig. 2 ise-similar ytofe central 'or rupture poras the length, and n the heatgenerated per unit of 1:25:11 is con-- i stant, and also that the 'heat 'ated per unit of length'will vary directly with the ex- 'd-surface per unit of length.- Now the strip :1 being originally uniform in cross section 18 changed to one of even cross secportions 2, the area of any section changed, 88 is also the amount of met unit of length i unper tion by' beingpros ided with the flattened -It will be apparent however,

that the flattened portions-2 present a much 7 greater radia surface than the central rupture portidh gand as the heat generated per unit of length is constant, the heat enerated in'tlie centralportion 3 be r iated less rapidly from th s portion than from the flattened portions 2; or in other words',;the heat generated is concentrated in the central portion 3 in which consequently the rupture of the strip is thereby effected, before the other portions of the fuse strip reach a molten and therefore 7 condition. We also find tmhe more or abrupt c connected to-said terminals and havinga central rupture-portion and adjacent portions of the same cross section as and greater,

heat radiating "surface than the said central rupture portions i 3. A safety fuse comprising a tube, end caps therefor, and a fuse strl electrically connected to said end caps and aving a central rupture portion and adjacent portions of the same cross section as and greater heat radiating surface than the said central rup-' .ture portion.

-4.. a'new article a fuse strip having a filling material within said tube.

central portion of circular section and ad acent portions of flat section.

5. As a new article a fuse strlilp having if central rupture portion of circ in section, and adjacent portions of flat section both sections being of substantially .the same sectional area.- I j 6. A safety fuse comprising a tube, terminals, a fuse strip havi a central portion of circular section and a jacent portions of flali; section, and a filling material within-said tu e. v

-7-. A safety .fuse comprising a tube, terminals, a fuse strip having a central rupture. portion of circular section, and adjacent portions of-flat section both section's being of substantially the same sectional area, and a a A si FRANK a). REYNOLDS. JOSEPH SACHS.

Signed by us this seventh day' 1906.

Witnesses:

WILLIAM -R. Cooxn, FRANK 'A. ALLEN: 

